Why has my baby stopped sleeping? What to do when your baby hits the 4 month sleep 'regression'.

Updated: a day ago

Why has my baby stopped sleeping? What to do when your baby hits the 4 month sleep 'regression'.

By Alissa Pemberton. Midwife, IBCLC & Gentle Sleep Coach


As a parent you will almost certainly have heard the phrase 'sleep regression'. As an already sleep deprived parent these milestones become periods that you dread. We're just waiting for the other shoe to drop, feeling like we shouldn't get too attached to any good nights of sleep we get, because that next sleep regression will be just around the corner.


What is a sleep regression?

This phrase is used to refer to a period where a baby's sleep patterns suddenly change, and they may appear to 'regress' to waking more frequently overnight, having more disturbed sleeps and having difficulty napping for long periods of time. The phrase 'sleep regression' naturally has negative consequences. By definition a regression is a step backwards. So is our baby really taking a step backwards? Or is it a giant leap forward in their development that causes changes to their sleep.

Personally I like to use the term 'sleep transition'. This is really what it is. Our baby is transitioning from one way of sleeping, through a period of rapid development, to another way of sleeping. It doesn't have to be a negative experience, and with consistency and understanding you can help your baby to sail through these periods as easily as possible.


Why do sleep transitions occur?

There are a few key times in your baby's early years when they go through rapid periods of development, and significant changes to the way they sleep. Both of these things usually cause temporary disturbances to their sleep patterns.

At around 4 months your baby may be:

- beginning to roll

- tracking people across the room

- sitting with support

- holding onto rattles/toys

- reaching out for objects


Behind the scenes of all of these new skills is a little brain working in overdrive. The little electrical impulses which pass between cells in their brains are firing 24 hours a day, meaning it's much harder for your little one to shut down and settle into sleep. Imagine yourself with a nerve wracking interview or a big deadline the next day - every found yourself lying in bed, wide awake, with thoughts rushing through your head? This is similar to what's happening for your baby. They may need extra assistance and extra time winding down before bed to allow them to 'shut down'.


There is also a huge change happening in the way your baby sleeps around this time. At birth, babies only go through 3 stages of sleep - NREM3, NREM4 and REM (or light) sleep. Newborns go straight from being awake, into a deeper stage of sleep, and then into light sleep, to awake again. They start to transition to a pattern closer to that of an adult's sleep at around 4 months - where they fall asleep through lighter stages of NREM1 & 2, then into deep sleep, then into REM sleep. This means their sleep cycle is slightly longer, but their brain is also adjusting to a completely new way of falling asleep.



Falling asleep through these lighter sleep cycles also means they are more easily disturbed, and more likely to wake soon after being put down, or after a particular sleep trigger is taken away (like rocking, singing, white noise etc.) because they're still in a light sleep and much more aware of their surroundings.

From about 12 weeks your baby is also starting to develop their own circadian rhythm (or body clock) and their body has now begun to secrete melatonin in response to changes in light/dark to help them get to sleep. This means they are now much more likely to be affected by the environment around them when they're sleeping.

Your baby is also likely to be going through the 4 to 3 nap transition around this age and it's very possible during this period that their nap times may be out of sync, or nap lengths might not be right for your baby's needs - resulting in a baby who is overtired and sleep deprived, or a baby who is sleeping too late in the day and isn't tired enough come bedtime. Ideally around this age you should avoid your little one napping later than 4.30pm-5pm. If you can't